I guess the x drive just senses no resistance and shuts off the front power. I've been led to understand you needed to pull the fuse to the motor that disengages the front axle.

I remember the guy who discovered he had no front driveshaft, I figured he had the equivalent fuse missing.

Good to know that the x-drive will keep on chugging when something blows up front but it should definitely give you an error when the front is disconnected why else is there a 4x4 error light on the dash?

The car doesn't have a separate sensor for wheel speed vs CV to detect a defect like CV pops out but it knows the calcuaked car speed from the transmission output shaft I guess only the rear wheels are accounted for in that math.

(Because the error that showed up in the his case was "transmission output speed too fast compared to wheel speed". ) it's very interesting that the front output is apparently ignored

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2011 E70 • N55 (me)
2012 E70 • N63 (wife)